MODELLING FROM THE PAST: THE LEANING SOUTHWEST TOWER OF CAERPHILLY CASTLE 1539-2015 (original) (raw)
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MODELLING FROM THE PAST: THE LEANING SOUTWEST TOWER OF CAERPHILLY CASTLE 1539-2015
Caerphilly Castle (1268-70) is the first concentric castle in Britain and the second largest in the UK. The dramatic inclination of its ruinous south west tower has been noted since 1539. Comparing data from historical surveys and a terrestrial laser scan undertaken in 2015, this paper seeks to review evidence for the long-term stability of the tower. Digital documentation and archival research by architects is collated to provide data for structural analysis by engineers. A terrestrial laser scan was used to create a detailed three dimensional finite element model to enable structural analysis of the current shape of the tower made by tetrahedral elements. An automated strategy has been implemented for the transformation of the complex three dimensional point cloud into a three dimensional finite element model. Numerical analysis has been carried out aiming at understanding the main structural weaknesses of the tower in its present condition. Comparisons of four sets of data: 1539, 1830, 1870 and 2015 enabled us to determine change albeit between very different methods of measurement.
The Open Civil Engineering Journal, 2012
The seismic behaviour of Maniace Castle, built on the Ortigia island in Syracuse (Italy) during the thirteenth century by Emperor Frederick II, was investigated by a numerical approach with the aim of comparing different strategies for structural reinforcement. The original building consisted of a square perimeter made by 4 m thick limestone masonry walls and round towers at the corners, embedding a large hypostyle hall. The roof of this main hall was supported by a system of arches, five on each side span. The current state of the castle is the result of subsequent interventions following the explosion that devastated the interior of the castle in 1704. Accordingly, at present the indoor hall consists of only 2/5 of the original covered area, and the primitive structural concept has greatly changed, since the double symmetry of the plant was substantially lost. Buttresses and transverse walls were added to improve the mechanical response to horizontal loads. Previous studies, both experimental and numerical, proved that the interior columns supporting the arches experience a level of vertical stress that is quite high in comparison to the actual strength. The situation is particular serious accounting for the seismicity of Syracuse, as a the significant increase in axial stress in the columns due to their flexural deformation might occur. In the present study, the behaviour of the castle is studied by means of a detailed full 3D FE model, both under vertical and lateral loads. The results of the analysis are used for a proposal of reconstruction of the hypostyle hall, bringing it back to the original geometrical configuration of the XIII century, by the use of modern building materials.
The 3D laser scanner has become a common instrument in numerous field applications such as structural health monitoring, assessment and documentation of structural damages, volume and dimension control of excavations, geometrical recording of built environment, and construction progress monitoring in different fields. It enables capture of millions of points from the surface of objects with high accuracy and in a very short time. These points can be employed to extrapolate the shape of the elements. In this way, the collected data can be developed to construct three-dimensional digital models that can be used in structural FEM analysis. This paper presents structural evaluation of a historic building through FE models with the help of a 3D point cloud. The main focus of the study is on the stone columns of a historic cistern. These deteriorated load bearing elements have severe non-uniform erosion, which leads to formation of significant stress concentrations. At this point, the 3D geometric data becomes crucial in revealing the stress distribution of severely eroded columns due to material deterioration. According to the results of static analysis using real geometry, maximum stress in compression increased remarkably on the columns in comparison with the geometrically idealized models. These values seem to approach the compressive strength of the material, which was obtained from the point load test results. Moreover, the stress distribution of the analysis draws attention to the section between columns and their capitals. According to the detailed 3D documentation, there is a reduced contact surface between columns and capitals to transfer loads.
Static behaviour of an Italian Medieval Castle: Damage assessment by numerical modelling
The paper offers a contribution to the issue of modelling and analysis of architectural heritage through the discussion of an illustrative case study: the Italian Medieval Castle of San Niccolò (Toscana, Italy). In the past the castle exhibited a wide damage, and to prevent its ruination, restoration works were executed in the eighties of the last century. Using the finite element technique, a 3D numerical model of the castle has been built that has been used to identify the main sources of the damages and assess the effectiveness of the restoration works. The paper shows that advanced numerical analyses could offer significant information both for the understanding of the causes of existing damage and the minimum and adequate design of strengthening. The understanding of the structural behaviour can indeed reduce the extent of the remedial measures, offering efficient strengthening tools.
Engineering Structures, 2017
In this paper, an innovative numerical modeling strategy for the structural analysis of historical monumental buildings is presented. The strategy is based on a procedure that enables the semiautomatic transformation of a three-dimensional points cloud surveyed through terrestrial laser scanner or closed range photogrammetry into a three-dimensional finite element mesh, as well as its mechanical characterization. Therefore, an increase of the level of automation in the mesh generation process is attained and a large reduction in the required time in comparison with traditional modeling procedures is achieved. In order to validate the new strategy, an application to the case study of the San Felice sul Panaro (Italy) fortress is carried out. The reliability of the proposed model is assessed through a comparison between the results of structural analyses and the crack pattern experienced by the structure during the Emilia earthquake (2012). Moreover, the vulnerability assessment of the main tower of the fortress is performed through simplified pushover analyses conducted on the generated mesh.
Remote Sensing, 2019
Terrestrial laser scanning is a widely used technology to digitise archaeological, architectural and cultural heritage. This allows for modelling the assets’ real condition in comparison with traditional data acquisition methods. This paper, based on the case study of the basilica in the Baelo Claudia archaeological ensemble (Tarifa, Spain), justifies the need of accurate heritage modelling against excessively simplified approaches in order to support structural safety analysis. To do this, after validating the 3D meshing process from point cloud data, the semi-automatic digital reconstitution of the basilica columns is performed. Next, a geometric analysis is conducted to calculate the structural alterations of the columns. In order to determine the structural performance, focusing both on the accuracy and suitability of the geometric models, static and modal analyses are carried out by means of the finite element method (FEM) on three different models for the most unfavourable col...
Structural assessment and seismic analysis of a 14th century masonry tower
Engineering Failure Analysis, 2019
The masonry building Heritage embraces a large variety of structural typologies, including churches, bridges, arenas, theatres, portals, castles, temples, and towers. The structural behaviour of these constructions appears often complex to be understood due to the uncertainties related to the materials and internal geometry. In this paper, a complete study (i.e. from the data acquisition and elaboration to the vulnerability analysis and proposal for a non-invasive strengthening procedure) of a monumental bell tower building is reported. An extensive program of structural and geometrical surveys has been planned and performed. The main goal of the breakdown was to assess the stability and the seismic vulnerability of the bell tower. Moreover, an innovative use of the drone-based survey for the computation of the geometry of the structure is proposed, in order to significantly reduce the time-cost expenditure of the structural assessment, without any significant lack in the accuracy of the measurements. The resulting object, obtained from the drone-based digitalized survey, was inputted and set in a Finite Element Method (FEM) code for structural modelling. Moreover, a nonlinear kinematic analysis was performed to individuate the possible failure mechanisms. Finally, a non-invasive strengthening procedure, aiming to the improvement of the seismic capacity, is proposed.
Fortifications of the Mediterranean Coast (FORTMED), 2023
Castles are complex fortified systems based on a solid relationship between the territory and the built architecture. The former defines the context of development, access, and defense conditions. The latter adapts to the context, proposing fortified structures in continuity with the orography of the territory. Both factors are crucial to understanding castles' historical evolution and social roles over time. In this knowledge path, the survey process assumes a primary role as a tool to analyze and interpret the built environment through bibliographic and iconographic analysis and the study of reality. Within the castle domain became essential to manage multiple scales of knowledge, acquisition, and representation, deepening the territory and the fortress systems. The case study analyzed is the Castle of Canossa, the epicenter of some critical events in medieval times. The authors describe an integrated survey process between active and passive techniques at architectural and territorial scales. Several geometrical validation steps have been introduced to verify the geometrical reliability. The pipeline highlights also the crucial relationship between territory and buildings, laying the groundwork for a more articulated analysis of the entire architectural complex. At the end, a superimposition between the geometrical model and a historical mock-up is suggested, collecting helpful information for the next reconstruction step.
Influence of the geometric model on the structural analysis of architectural heritage
Journal of Cultural Heritage, 2020
Geometric models employed for structural analyses are usually strongly simplified, in order to make easier and faster the numerical solving. Sometimes this approach is valid and convenient as far as it does not influence the analysis results. However, depending on the circumstances and the objectives of the analysis, the model has to be accurately and precisely represented to capture the necessary outputs. This is the case with architectural heritage. In fact, in this field, the surveyed objects are often characterised by complex forms and remarkable damages, which can affect the geometry significantly. Nowadays, many techniques are available to obtain very detailed models of the surface of the object, but they do not allow to consider also interior damages or the constructive features. This information can be obtained through a careful knowledge and anamnesis of the object to study, based on visual inspection and instrumental measures. In this way, the creation of the model to undergoes to a structural analysis, consists in a synthetic operation conducted by the operator in a conscious way. This paper aims to prove that the results of a structural analyses can change significantly, depending on the accuracy and the level of detail of the model. The study was conducted on a basic building element, that is a column, really existing and belonging to a monumental fountain. The column was modelled in five different ways which differ in the level of detail. An ultrasonic test was conducted on the real object to characterise cracks which were taken into account in the most accurate models. A comparison among the five models was done from a static and dynamic perspective, through the following analyses: static, buckling, modal and dynamic with response spectrum.
Numerical Analysis of Historic Structural Elements Using 3D Point Cloud Data
The Open Construction and Building Technology Journal, 2016
The 3D laser scanner has become a common instrument in numerous field applications such as structural health monitoring, assessment and documentation of structural damages, volume and dimension control of excavations, geometrical recording of built environment, and construction progress monitoring in different fields. It enables capture of millions of points from the surface of objects with high accuracy and in a very short time. These points can be employed to extrapolate the shape of the elements. In this way, the collected data can be developed to construct three-dimensional digital models that can be used in structural FEM analysis. This paper presents structural evaluation of a historic building through FE models with the help of a 3D point cloud. The main focus of the study is on the stone columns of a historic cistern. These deteriorated load bearing elements have severe non-uniform erosion, which leads to formation of significant stress concentrations. At this point, the 3D ...